Projectile



July s, 194?.

J. V. HOWE PROJEGTILE Filed May 13, 1942 gmc/whom' Jume5Y HmwE Patented July 8, 1947 STT E S ENT eprice Claims.

(Granted under The invention described herein may be manufactured and used by or for the Government for governmental purposes, without the payment to me of any royalty thereon.

This invention relates to iirearms generally, and particularly to means for providing a large area of the projectile to be exposed to the propulsion gases, without however increasing that area of the projectile which resists its travel through the atmosphere.

Ballistics experts and gun designers have always been confronted with the problem of constructing a gun capable of imparting a high. velocity to the projectile. The need for higher velocities in projectiles has increased with the advent of heavier armor for combat vehicles.

Solution of the problem is made more difficult by the fact that the projectile should have a large area exposed to the propulsion gases during its travel through the gun, so that the working pressure of the gases may exert a large force on the projectile, yet the area of the projectile should be as small as possible when the projectile moves through the atmosphere, so as to reduce air 1esistance to a minimum. Further complications and contradictions arise out of the fact that the projectile should be given a turning or rotating motion about the axis parallel to the direction of motion, but in order to impart to the projectile this rotary motion it is necessary to divert some of the energy of the propulsion gases which goes toward giving the projectile its forward velocity. Furthermore, the means used to impart aturning motion to the projectile serves as a mechanical retarding force, in that the raised lands of the rifling actually increase the friction between the projectile and the bore of the gun, serving to hinder acceleration of the projectile.

It is the object of this invention to provide a projectile and a gun in which the projectile eX- poses a large area to the pressure of the propulsion fluid and a small area to the atmosphere, and in which the desired turning motion is imparted to the projectile with a minimum of interference with the forward acceleration of the projectile. This object is achieved by the provision of a casing or shell of combustible material to increase the transverse dimension and therefore the cross sectional area of the incombustible member which comprises that portion of the projectile propelled through the atmosphere. The

amended April 30, 1928;

combustible casing or shell, known as a sabot, is gradually burned away in a combustion chamber which converges forwardly. Rotary or turning motion is imparted to the projectile by riindicated the act of March 3, 1883, as

fling, but to reduce the retarding effect of the resultant friction to a minimum, the rifling extends throughout only a fraction of the bore, there being no rifling at all in the combustion chamber.

The specific nature of the invention as well as other objects and advantages thereof will clearly appear from a description of a preferred embodiment as shown in the accompanying drawings in which:

Fig. l is a longitudinal view, with parts broken away and in section, showing a gun barrel compllete with energy producing charge and projec- Fig, 2 is a rear end or face view of the cornplete projectile.

Fig. 3 is a View in section substantially on the line 3-3 of Fig. 2.

Fig. 4 is a rear end view of the envelope for the sabot.

Fig. 5 is a View in section substantially on line 5-5 of Fig. 4.

In the drawings is shown a gun comprising a barrel 2 having a longitudinal bore therethrough generally by il. At one end of the barrel the bore is enlarged as at 5 to receive a charge 8 of a suitable substance capable of producing energy when desired. The charge 8 will normally be a predetermined quantity of propellent powder of a desired composition, enclosed in a cartridge case Hl, At the forward end of the case is secured a projectile indicated generally by I2, which will later be described in detail. Projectile IZ and that portion of case l0 containing it are housed in a chamber I4 formed in the gun bore. It will, of course, be understood that case I0 may sometimes be dispensed with, in which event projectile l2 will rest in chamber l in immediate contact with the walls thereof. Charge 8 may or may not then be enclosed in one or more combustible envelopes, as desired.

Immediately forward of chamber I4 is disposed a combustion chamber le, which is preferably tapered or convergentforwardly as shown to snugly receive the transverse dimension of advancing projectile l2 which is being reduced by combustion of the combustible casing or sabot. Chamber l preferably has smooth walls, to provide a minimum of resistance to the passage therethrough of the pIOJ'eCtile.

Chamber I6 converges or tapers down to a dimension which is substantially that of the projectile proper, or that portion of the projectile which is adapted to be propelled through the `at mosphere. Immediately forward of chamber I6 is a preferably smooth bore chamber i 8 having a substantially constant transverse dimension throughout its length. This dimension also is substantially the same as the transverse dimension of the projectile proper.

In order that the portion of the projectile leaving the gun have the desired turning or rotary motion, bore i is provided with riiiing 2t, as will be understood by those skilled in the art. Prei erably, only a portion of the length of the bore will be riled, in order to provide a minimum of resistance by the rifiing to acceleration of the projectile, although it will, of course, be understood that the entire constant-diametei` portion of the bore may be riled.

Referring now to Figs. 2 to 5, it is seen that projectile EE comprises an incombustible, usually metallic, member or bullet 222 which is preferably generally cylindrical, but pointed or tapered forwardly in ogival form as at 2d. Member is moreover preferably tapered, o-r made to c verge, rearwardly into boat-tail form as shown to decrease the air resistance. Member 22 has a predetermined maximum transverse dimension, usually a diameter, which in this case 1s the diameter of rotating band 22. The cross-sectional area presented by member 2 to the atmosphere through which it moves will thee. depend upon the transverse dimension, or diameter, of band 28.

In order that projectile i2 may present a greater cross-sectional area to the iluid pressure while it is exposed thereto or during a portion of that time, a casing or sabot 3e of a combustible material is provided along at least a portion of the length of member or bullet 22. Sabot Se may be made up of either a single base or double base powder reduced to a soft plastic mass by the use of suitable solvents. The mass may then be formed about member 22 by any of a number of well known means, such as injection molding, or the plastic mass may be molded into pellets, each of which is then formed around a member 22 under hydraulic pressure. Sabot E@ will preferably itself be encased in an envelope 32, which. may be of any suitable combustible substance, such as paper covered with shellac, paper or shellac alone, Cellophane, or the like. The envelope may even be made of metal. Sabot 3! and envelope 32 will preferably be made to converge forwardly, as shown at 3d.

A single or double base powder, molded into such a body as shown, is very rigid. However, ii it be found that the sabot tends to burn away too fast, leaving the projectile proper suspended in the center of the combustion chamber, a sub stance such as camphor can be used in the material of the sabot to slow down the burning time. The burning time can thus be adjusted so that combustion of the sabo-t is completed when the projectile leaves the combustion chamber.

To facilitate and expedite the combustion of sabo-t 33 during the passage of the projectile through chamber i6, the rear face or surface of the shell is formed with openings which may be conical indentations, as shown. lndentations 32 serve to increase the surface area exposed to the burning gases.

claim:

1. A projectile comprising e, body portion, a sabot of propellent material enveloping the sides and rear of said body portion, said sabot having a generally cylindrical outline and a forward, truste-conical shoulder meeting the body portion medially thereof, and an o-uter, metallic covering for the cylindrical and truste-conical portions of said sabot.

2. in a projectile as in claim l, cavities in the rear face of said sabot.

3. In a projectile for use in a gun having a bore section tapering forwardly from a rst diameter to a second diameter, a bullet having a maximum diameter substantially equal to said second diameter, and a sabot enclosing the rear portion only of said bullet, said sabot comprising a rigid generally cylindrical body of explosive having a diameter substantially equal to said rst diamete'.-1 and means positively attaching said sabot to said bullet, said sabot acting as a guide for said projectile during its passage along said bore section.

In a high-velocity projectile for 'use in a gun having a smooth tapered bore section, said projectile comprising a bullet having an ogival nose and a circumferentially grooved body, the greatest diameter of said bullet being substantially equal to the diameter of the smaller end of said bore section, and a sabot completely surrounding the rear portion only of the body of said bullet, said sabot comprising a rigid body of propellant having a generally cylindrical exterior surface of the diameter' of the larger end of said bore section and rigidly attached to said bullet by engagement with said grooves, whereby said sabot acts as a guide for said bullet during its along said bore section.

5. A projectile as in claim 4, said sabot including a metallic cylindrical envelope enclosing said body of propellant, said envelope having an open rear end and tapering at its forward end int-o contact with the body of said bullet.

JAMES V. HOY/VE.

REFERENCES CITED rihe following references are of record in the le of this patent:

UNITED STATES PATENTS Number Name Date 1,944,883 Gerlioh Jan. 30, 1934 1,127,268 Malster Feb. 2, 1915 2,121,796 Helbich June 23, 1938 128,446 Winchester June 25, 1872 1,141,042 Davis May 25, 1915 702,268 Hayner June 10, 1902 1,166,360 Gregory Dec. 2S, 1915 1,669,969 Caruth May 15, 1928 FOREIGN PATENTS Number Country Date 2,09) Great Britain Feb. 14, .1.335 

